The invention relates to a mechanism for continuously taking test specimens or samples, such as from sludges or pulps, wherein the sample is accurately representative of the flow of material. More particularly, the invention relates to a mechanism for flowing fluid material gravitationally downwardly and taking a sample truly representative of the flow and passing that sample to another chamber where another sample is taken representative of flow and thereafter passing the second sample to a third chamber where another sampling is taken.
Sampling devices for test specimens from pulps or sludges have been known before in the art, and an example of such device is shown in German Pat. No. 745,782. In this patent a sampling spoon is moved back and forth and driven by an electric motor which drives the device to move the spoon in arbitrarily regulable periods of time through the stream from which the sample is to be taken. The sampling spoon is carried by an arm driven by the motor and a time switch controls the mechanism so that the samples are taken from the stream of liquid noncontinuously. The sampling spoon is connected with the discharge conduit inclined downwardly through which the test specimen flows to a collector.
The operation of such a sampler requires the constant supply of driving energy and, of course, requires operating parts which exhibit wear with the passage of time. Also, a timing mechanism must be provided which must be reliable and requires that a source of operating power for the timer be provided. Also, by the nature of such a structure, it must operate intermittently, and therefore, it is not possible to actually take a continuous sample, which can lead to inaccuracies in sampling.
An object of the present invention is to provide a mechanism which furnishes a fully representative sample of fluid material, such as liquid sludges or pulps, which avoids disadvantages of samplers heretofore available and by which a truly continuous withdrawal even of an extremely small quantity of a sample is made possible from a large quantity of flow. The mechanism is practical for use in laboratories which have high requirements with respect to the representative nature of the samples and provide such a sample which can be used for analytical control or for supervision of a process.
A feature of the invention is to provide a chamber through which the material flows gravitationally with the lower area of the chamber constructed as a sample divider having a plurality of passage openings. The chamber is constructed so that flow will be fully uniform and representative through each of the passage openings, and the sample is removed through an takeoff passage receiving flow from only one or a small number of the passage openings. Since the passage openings are uniform in size, location, and shape, and relationship to the main flow through the chamber, a fully representative sample is taken, and the flow continues through the chamber with the fluid continuing to mix homogeneously. By the use of gravitational flow, the power requirements of previous devices is eliminated and losses of material occurring due to erratic operation or power failure are eliminated.
In accordance with the principles of the invention, the lower chamber area is constructed rotatably with respect to the upper chamber area, and the lower chamber area has a sample divider plate with the openings being a plurality of radially extending slots which increase in width radially outwardly. By interchange of plates with different size openings or by selectively blocking a portion of the openings in a uniform manner so that the flow through the remaining areas is representative, the quantity of continuous sampling can be controlled.
In providing a divider plate wherein the passage openings are radially extending slots, a uniform impingement of the flow of material against the plate is obtained and is particularly useful in sludges or pulps. In these types of flows, the formation of strands or build-ups of coagulated or concentrations of materials can occur in ordinary devices, but is avoided so that by the taking of samples, the homogeneity of the flow is not destroyed.
In the preferred embodiment, the initial chamber, and subsequent chambers are cylindrically shaped with the inlet discharging tangentially into the upper area of the chambers. This invokes a whirling movement of the liquids to prevent settling out or coagulation which can occur in sludges or pulps, particularly at the area of the inlet where whorls or whirlpools can form having an adverse effect on the even distribution of the material in suspension in the liquid. By continuing the uniform distribution of material throughout the liquid the quantities of samples drawn off are fully representative and are an average of the flow of the entire quantity of material. This is particularly important wherein statistics to be produced from the samples indicate analytically the results of a process through which the material has been subjected or control the process to which the material is to be subjected later.
In the cylindrical chamber beneath the inlet is arranged a frustoconical distributor shield with a central opening discharging downwardly toward the sample divider plate. This complements the whirling action of the material entering the chamber tangentially. Directly below the frusto-conically shaped downwardly depending skirt is an upwardly extending cone positioned in the center of the distributor plate with the radial openings extending outwardly and arranged symmetrically around the cone. With this arrangement, the flow through the skirt and onto the cone will be distributed uniformly out over the sample divider plate and over the passage openings so that each passage opening is equally impinged as to quantity of material. The sampling is taken from at least one of the passage openings which discharges downwardly into takeoff passage with the takeoff passage feeding to a second chamber constructed similarly to the first chamber, and an takeoff passage from the second chamber delivering to a third chamber from which a sample is taken. Thus, the first sampling removes only a small representative part of the total flow, and the second sampling represents a small representative part of the first sampling, and the third sampling removes only a small representative part of the second sampling so that the final sample is a very minute part of the whole, but truly representative thereof.
In the construction of the chambers, the lower portion is removable so that the sample divider plate can be readily and quickly exchanged to provide a new plate with different size openings for different sample requirements. In the arrangement above described, the several chambers are arranged in sequence so that the fluid continues to flow gravitationally, and the gravitational flow is channeled and handled in such a manner so as to maintain uniform flow about the central axis of each of the chambers and with the flow continued to be agitated in a manner so that the fluid is homogeneous at all circumferential locations. The rejected portion of the first sample and of the second sample are fed back into a main discharge from the main chamber with the entire unit constructed so as to require relatively small headroom and minimum restriction to flow of the fluid being sampled.
Other objects, advantages and features of the invention will become more clear, with equivalent structures and methods which are intended to be covered hereby, in the disclosure of the specification, claims, and drawings in which: